Two-thirds of the inhabitants of Manus Island Regional Processing Centre in Papua New Guinea have demanded help end their own lives to escape being 'tortured and traumatized' every day.

Hundreds of refugees are thought to have signed an open letter calling for mass assisted suicide in the Australian immigration detention Centre where they are being held.

Around 600 asylum seekers at the Manus Island Regional Processing Centre, on an island off the coast of Papua New Guinea, are believed to have put their names to the letter.

Manus Island, home to 900 refugees, is one of several detention centers responsible for processing people attempting to get to Australia on boats.

Australian immigration lawyer Julian Burnside posted a transcript of the letter on his blog on Monday.

It called on Prime Minister Malcolm Turnbull and Immigration Minister Peter Dutton for "a navy ship that can put us all on board and dump us all in the ocean... a gas chamber... (or) an injection of a poison".

It said: “As previously we wrote and asked for help and there was no response to our request to be freed out of detention we realized that there are no differences between us and rubbish - but a bunch of slaves that helped to stop the boats by living in hellish condition.

“The only difference is that we are very costly for the Australian tax payers and the politicians as our job to ‘stop the boats’ is done.

“We are dying in Manus gradually, every single day we are literally tortured and traumatised and there is no safe country to offer us protection.” , foreign media reports.